A hermetic seal is an airtight seal which is impermeable to water in the liquid or vapor state. Hermetically sealed electronics modules are components that are designed and intended to secure and maintain the safety and quality of their contents. Hermetically sealed modules may be sealed utilizing a variety of processes including soldering, brazing or diffusion bonding such as with an indium-tin bond. Electrical interconnect to these sealed modules is provided with hermetic connectors that typically include glass frits that surround the electrical conductor and provide a seal between the hermetic module housing and the conductor.
Although diffusion bonded seals typically perform very well, they have been found to occasionally leak after rigorous mechanical shock and vibration testing. The cause of the leaks is due to failure at the metallic seal, which can be gold-tin, indium-tin, etc. depending on the sealing method used. This failure is often related to the formation of brittle intermetallics (alloys of two or more metals in a certain proportion, forming a new chemical compound) and corrosion. In addition, stresses induced by thermal expansion mismatch between the module housing and the glass frits in hermetic connectors can cause cracks in the glass which break the hermetic seal and can allow moisture penetration. Attempts have been made to utilize varnish to seal these cracks, but varnish is not hermetic. Opportunities to improve or repair hermetic seals and hermetic connectors are limited due to the requirement to maintain relatively low bonding temperatures to avoid damaging the electronic components within the sealed module.
Consequently, it would be desirable to provide a simple, low-cost, low-processing temperature method for hermetic seal and hermetic connector reinforcement, repair, and corrosion protection.